Why it matters on an HVAC site
The common case is the service-area map. A widget fetches the list of towns served and draws them, which means the towns exist in the rendered page and not in the HTML. If those towns are the only place the site says where it works, the site has not said it in a form that survives a failed render.
The second case is a menu built as a script-driven dropdown with no real links behind it, which turns every page below it into an orphan.
How to check it yourself
- Fetch the raw HTML and search it for the content in question, then compare against the rendered DOM. Anything present only in the second is render-dependent.
- Search Console URL Inspection shows the rendered HTML Google actually built, which is the authoritative version.
- Disable JavaScript in the browser and use the site. What you can still reach is what a failed render leaves.
Worked through in numbers
A contractor’s 34 service areas are listed by a map widget. The raw HTML contains none of the town names.
URL Inspection shows Google rendered the widget successfully, so the towns were being seen. But the widget produced no links, so the 34 town pages had no internal links at all and averaged position 68.
Adding a plain linked list of the 34 towns beneath the map, present in the HTML, kept the map and gave the pages a route in. The map was never the problem; the absence of links was.
Where this sits in the rankings
Scored under Technical SEO. What happens when the content only exists after a script runs.